Tag: dendrochronology

I was travelling last week. I was sitting outside this bar, having just eaten and had a couple of beers when this quite awkward looking middle-aged man approached my table sheepishly and asked if he could sit there. I looked up and as he looked harmless enough I consented with a nod. He sat down and I guessed he was travelling alone and probably looking for someone to talk to. So I struck up a conversation and went through the usual; ‘what brings you here’, ‘what do you do’ etc. He was a little reluctant to tell me at first what he was there for. Perhaps he assumed that I was being polite but would find it rather boring but I pressed on and this is what he actually told me:

The story begins in 1929 when Andrew Douglass pioneered a scientific method called dendrochronology or ‘tree ring dating’. He was the first scientist (in modern times; some say da Vinci discovered it) to discover that tree rings record time. Its concept is simple. You cut down a living tree then count the number of rings which would give you the number of years it has lived as well as from which to which years it lived. But it gets a little tricky if you don’t know when the tree was cut down. It would tell you how long it lived but not necessarily when it lived and died. But by comparing trees across the same region and climate, Douglass noticed that trees develop rings in the same patterns; hence by creating a database of trees with known living date(s), and comparing their rings to the pattern of unidentified tree samples, you could nail down the dates (in years) those trees lived in.

Now moving onto radiocarbon dating – when tree ring dating isn’t possible due to lack of comparable dated tree samples, carbon dating comes very handy. A radioactive isotope of carbon called Carbon-14 or C14 is in every living organism. And since some clever chaps discovered its half-life, it’s possible to date pretty much anything within the accuracy of 50 or 100 years.

Then there is this thing called solar storm. It’s a powerful explosion on the sun, whose energy can be likened to thousands of nuclear bombs exploding at the same time. In 1989 this actually happened when the magnetic forces and a cloud of gas rushed to the Earth at a million miles an hour, and the solar flare from this solar storm shut down the entire power grid in the province of Quebec.

Now researchers found that trees that live(d) through short term events, like solar flares or volcanic eruptions record unusually high levels of radiocarbon content up to 20 times the normal level. Long story short, through calibration by using carbon-dating in conjunction with tree-ring dating, solar flares or volcanic eruptions can act as chronological anchors to more accurately date things.

So why had this guy I randomly met told me all this?

Well, some of you might be familiar with the eruption of volcano in Thera (now called Santorini) in the Aegean Sea, which supposedly happened anytime between 1645 BC to 1500 BC, which historians suspect created large tsunamis that significantly damaged the nearby island of Crete, the then centre of the Minoan civilisation. This makes the date of this volcanic eruption a turning point in the history of Western civilisation. Depending on which year these researchers settle on, they might have to re-write a significant chunk of the history as we know it, rendering a lot of what we know rubbish.

So, this guy was an archaeologist on his way to collect a wood sample they think they found which could potentially determine this date once and for all.